I get it in Ohio, no problem.

If flooding it won't work, try the "soft nylon string" into the cylinder and gently turn the crank (with a prop) up towards TDC. Don't force it though; if it needs more than gentle hand pressure, better to take it apart and tap the contra back and forth with a wooden dowel. You'll lose your nice fits but that's better than a bent rod or pin.

I've fixed a sticking contra piston on a couple of diesels, last one was a Frog 150 I bought in un-run condition. Remove the contra piston & wedge a 2" or so piece of slightly oversize wooden dowel into the top recess as tight as possible. Put the dowel in the chuck of a drill or lathe, run it & lightly "sand" it with fine wet & dry paper but only for a few seconds. Remove, clean well with meths or petrol (gas), lubricate with a drop of light oil & try in the bore. Repeat if necessary but be careful not to overdo it or you'll end up with a loose cp.

Jimmy, you said, “Once it was running the contra piston would not back out allowing the compression to be lessened”.
How well was the diesel running, ie) just right or over compressed (black smoke and sounding unhappy?)
If it was running “ok” try running it a little more leaving the compression screw backed off, or take it out. It may loosen off on it's own.
Jack’s suggestion is good.
You might also try heating the outside top area with a hot air gun (up to operating temperature or a little higher), then flipping the prop. Put the engine in the freezer, remove and quickly heat up, flip, try again.
Do not force the piston up, you may bend the rod.

Putting my finger over the intake while it was running did the trick. I did battle with it and a PAW .03rc today-- right now my neck and shoulder are losing.

Success with the Merco.
A few posts back I posted a few pictures of a used Merco diesel. I got it apart except for one very stubborn head bolt that just would not budge. I had suggestions of cutting the bolt head off using a fine hack saw held between the cooling fins. Luck was on my side. In trying to torque the bolt, the head broke off. Now, I thought, this is going to be easy, just grab onto the bolt threads and torque it out. No such luck. I broke the bolt again, but a small section remained sticking out. After months of sonification (in AT and acetone), heating, using a vibrating engraver on the stud, more heat, penetrating oil, I finally got the bolt out. I think the previous owner used lock-tight. Re-tapping the threads to clean them out brought up a lot of “residue”. I’ll post pictures later of the Merco.

Kroil is a wonder penetrant available here in the states. It does everything from cleaning firearms to removing warts.

Originally Posted by Tag1260

For those of you making your own fuel, in the USA, what specific brands of ether are you finding that work. I know John Deere but am having a problem getting it.

HEET from ACE hardware, is the only stuff that I have seen in the UAE, for sure I can't get John Deere! I have no idea what the actual concentration of Di-ethyl ether is, but it seems to work alright on the small diesels I have.
sparks

Here's the residue from the broken head bolt in the Merco

see post 977 page 66, this shows the exhaust area and if you look closely, a small crack which shows up later.

and

the unknown diesel

JohnAV8R,
Have you run this Merco 5cc? if you have, what is your opinion of it?
I have one brand new in box and don't know whether I should contemplate using it or keep it as a collector item. It doesn't seem to be in the same league as the two Merco 49's I have.

JMP, no I haven't run this Merco. It's totally apart, will take pictures and post.
It is not of the overall quality of the old .49, .60 twin plug motors. This one has an excellent piston/cylinder fit, but a poor crank case, no bearings, not even a bronze one for the crank. The metal on the carb is also badly pitted. I suspect the first owner did not know much about the motor and did not run it much, other than to "gum" it up. What you see, isn't always what you get.
On the other hand, the "unknown" is very crudely made, probably due to lack of good tools.

Here are the parts of this diesel.
The broken bolt stud was clamped in a vise and the engine "twisted" to torque the bolt into unscrewing.
This unit had been soaking in a sonicator, AT/acetone fluid mix since July.

A closer look at the crank case shows what was there.
The crank case (1980's ??) is not up to the "old Merco" standards.
Adding BB or a bushing would have really helped out with this engine. Lack of makes it questionable quality?
Some parts appear very well made, others are lacking from an engineering point of view. A little like the mix of the good and the bad led to a mediocre product.

How many of these diesels are around?
Are many of you still using them? If so, how well have they held up?

Here are some of my diesels .

Mike1484